354 Mr. R. Gurney on certain 
investigation of the life-history of this, our only remaining 
British Phyllopod, are required. 
CLADOCERA. 
The two species mentioned below were both found during 
August and September 1919 on East Ruston Common, 
three miles north-west of Stalham, in East Norfolk. At 
the spot where I have made my-collections the marsh is 
crossed by a road at its narrowest part, and on the south 
of the road is a bog which is always under water. There 
is a rich vegetation of the usual fen type, with a dense 
growth of Hypnum below the water, with which is mingled 
Utricularia minor and intermedia. The presence of Chara 
in a pool in the marsh indicates a calcareous water. The 
Entomostracan fauna is of remarkable richness, and differs 
in several respects from that of any waters with which I am 
acquainted. Twenty-four species of Cladocera and twenty 
of Copepoda have been found in a small space of a few square 
yards, besides several Ostracoda ; while some of the species 
are extremely rare in other parts of the district, but occur 
here in considerable numbers—-for example, Metacypris cor- 
data, Cypris fasciata, Candona euplectella, Cyclops nanus, 
and Canthocamptus northumbricus. The two species, Cerio- 
daphnia setosa and Kurzia latissima, were found only in this 
one small spot and not elsewhere in the marsh. 
2. Ceriodaphnia setosa, Matile. (Fig. 1.) 
A few specimens of this peculiar Ceriodaphnia were found 
in a collection made on Aug. 26 in moss under a depth of 
about six inches of water. I returned to the spot two days 
later with the intention of obtaining more material, but was 
again rewarded only by a very few individuals in spite of 
exhaustive search, and was not able to ascertain in what 
kind of situation it was living. Its almost entire absence 
from collections made in the clear open water seems to show 
that it lives actually among the moss, whereas C. laticaudata, 
which was also present at the same time, was commoner in 
the open water. C. setosa is a sluggish swimmer, and is 
easily distinguishable from the usual red form of C. lati- 
caudata by its whitish colour faintly tinged with rose ; but 
this character is not altogether distinctive, since I have 
found C. laticaudata in abundance in a similar situation at 
Sutton Broad, every individual being of exactly the same 
colour as C, setosa. In fact, I supposed at the time that I 
had found a new habitat for the latter. 
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